COST OF CHARGING WITH A LEVEL 2 CHARGER HYPOTHETICAL

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BillThompsonMIEV

Well-known member
Joined
Jul 19, 2012
Messages
137
Location
San Antonio, Texas
I am probably showing my ignorance here. My electricity costs ten cents per KW hour. If I use a Level 1 charger (OEM) for five hours it costs me $.50 for electricity. We all know a level 2 charger works faster. So, if I charge for five hours with a Level 2 charger, more electricity is added to the the car. Is my electic cost still $.50? If the answer is yes, then a Level 2 charger in the long run is more effective. Obviously the cost of the Level 2 charger has to be taken into account. I am just wondering if a Level 2 charger is more effective in the long run as to electricity costs.
 
Since more electricity is added to your car, your cost of electricity will also increase based on how many kwh you fill your Miev with. In five hours you could expect to use 15kwh so basically $1.50. The use of a level 2 charger is more efficient in that there are smaller losses of kw's and your unit is on for only 5 hours as opposed to 15+ hours if you were to try to get the same amount of charge with a Level 1.
 
Bill,

Electrical energy is measured in killowatt-hours (kWh), which is power (in kilowatts) over a period of time (hours). Let's say you pay ten cents per kWh.

Using a Level 1 (120vac) EVSE, the iMiEV charger draws 900watts. In five hours you put 4.5kWh into the iMiEV at a cost of $0.45. If you continue charging for a total of 16.67 hours you will put in 15kWh into the iMiEV at a cost of $1.50.

Using a Level 2 (240vac) EVSE, the iMiEV charger draws 3000watts. In five hours you put 15kWh into the iMiEV at a cost of $1.50.

The COST of stuffing a given amount of energy into the car is the same. What the higher voltage gives you is the ability to recharge the car faster.

Another way of looking at this is to think of kilowatt-hours as gallons of gasoline. It doesn't matter how fast you pump the gasoline into the car, the cost per gallon is the same. The 240vac "pump" is simply faster than the 120vac "pump", but it's the number of gallons (or kWh) you stuffed into the car that you pay for.

Hope this answers your question.
 
No savings (or loss) at all. A 240 charger is like a larger hose on a gasoline pump - You refuel faster, but receive the same quantity (and cost) of energy. One kilowatt hour of electricty is ten cents (or whatever your cost is) no matter how quickly you put it into the car

If you're interested in 'refueling' faster, consider sending your OEM charger off to EVSE Upgrade - They will convert your 8 amp 120 volt charger into a 12 amp 120/240 charger. Using 240 volts at 12 amps will put 14.4 Kw into the car in 5 hours, whereas the stock EVSE needs 15 hours to do the same thing, so all your recharging can be done in 1/3rd the time

Don
 
Don said:
No savings (or loss) at all. A 240 charger is like a larger hose on a gasoline pump - You refuel faster, but receive the same quantity (and cost) of energy.
Don

Have talked to a few electricians who have told me that higher charging rates provide less electrical resistance and thus less efficiency losses. Realize that the savings may be minimal per use but may add up depending on how often one charges their vehicle.
 
That's true . . . . in a sense

Given equal loads, a 240 volt circuit uses only half the current of the same thing done with 120 volts (120 volts at 20 amps is 2400 watts and so is 240 volts at 10 amps) so theoretically, the resistance losses in the 240 volt circuit are less - If you use identical wire sizes in both cases, they are definitely less, though you'd have a hard time comparing the losses as they are very small

Usually though, wire is sized by the current flowing in the circuit. Here in the USA, we use 12 gauge wire in most electrical outlets because they are usually rated at 20 amps, and 12 is the correct size for 20 amp circuits. In Europe where everything is 240 volts, wire sizes are smaller because the same load requires only half the current - A 2400 watt load is only 10 amps, so no need for 12 gauge wires. The savings in wiring everything with smaller gauge wiring is significant in this day and age - 240 is definitely the way to go. A 100 foot 20 amp extension cord is now around $50 . . . . it would be about half that if it was used for a 240 volt system because the wire size would be smaller and it would contain about half as much copper. European outlets are far superior to ours as well - There is no way you can shock yourself plugging in a cord there . . . . the pins on the plugs cannot be touched once they are 'live' whereas ours can be

It's unfortunate that we never switched over to a complete 240 volt system like they use in most other parts of the world 50 or 60 years ago when it was proven to be so advantageous - We did make that switch in automotive electrics in the 1950's when 6 volt systems were proven to be inferior . . . . why we didn't carry that over to all AC circuits is a good question - Maybe because copper was so inexpensive back then (it was once so cheap we used it to make pennies) it was decided that we should just continue to go ahead with our 120 system using larger wiring?

Don
 
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